• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.24-32
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• 2017

In this paper, a low power 4th order delta-sigma modulator was designed with a high resolution of 12 bits or more for the biological signal processing. Using time-interleaving technique, 4th order delta-sigma modulator was designed with one operational amplifier. So power consumption can be reduced to 1/4 than a conventional structure. To operate stably in the big difference between the two capacitor for kT/C noise and chip size, the variable-stage amplifier was designed. In the first phase and second phase, the operational amplifier is operating in a 2-stage. In the third and fourth phase, the operational amplifier is operating in a 1-stage. This was significantly improved the stability of the modulator because the phase margin exists within 60~90deg. The proposed delta-sigma modulator is designed in a standard $0.18{\mu}m$ CMOS n-well 1 poly 6 Metal technology and dissipates the power of $354{\mu}W$ with supply voltage of 1.8V. The ENOB of 11.8bit and SNDR of 72.8dB at 250Hz input frequency and 256kHz sampling frequency. From measurement results FOM1 is calculated to 49.6pJ/step and FOM2 is calculated to 154.5dB.

• Economic and Environmental Geology
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• v.32 no.5
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• pp.469-483
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• 1999

Two different types of deep groundwaters occur together in the Jungwon area: $CO_2$-rich water and alkali water. Each water shows distrinct hydrogeochemical and environmental isotopic characteristics. The $CO_2$-rich waters are characterized by lower pH(6.0~6.4), higher Eh (25~85mV) and higher TDS content (up to 3,300 mg/l), whereas the alkali type waters have higher pH (9.1~9.5), lower Eh (-136~-128mV) and lower TDS content (168~254 mg/l). The CO2-rich waters ($Pco_2$=up to 1atm) were probably evolved by the local supply of deep $CO_2$ during the deep circulation, resulting in enhanced dissolution of surrounding rocks to yield high concentrations of $Ca^{2+}, Na^+, Mg^{2+}, K^+\; and \;HCO_3\;^-$ under low pH conditions. On the other hand, the alkali type waters ($Pco_2$=about 10-4.6 atm) were evolved through lesser degrees of simple wate/rock (granite) interaction under the limited suppy of $CO_2$. The alkali waters are relatively enriched in F- (up to 14mg/l), whereas the F- concentration of$CO_2$-rich water is lower (2.2~4.8 mg/l) due to the buffering by precipitation of fluorite. The oxygen-hydrogen isotopes and tritium data indicate that compared to shaltion ($\delta$18O=-9.5~-7.8$\textperthousand$),two different types fo deep groudwaters (<1.0TU)were both derived from pre-thermonuclear (more than 40 years old) meteoric waters with lighter O-H isotopic composition ($\delta$18O=-9.5~-7.8$\textperthousand$) and have evolved through prolonged water/rock interaction. The $CO_2$-rich waters also show some degrees of isotopic re-equilibration with $CO_2$ gas. The $\delta^{34}S$ values of dissolved sulfates (+24.2~+27.6$\textperthousand$) in the $CO_2$-rich waters suggest the reduction of sulfate by organic activity at depths. The carbon isotope data show that dissolved carbon in the $CO_2$-rich waters were possibly derived either from dissolution of calcite or from deep $CO_2$ gas. However, strontium isotope data indicate Ca in the $CO_2$-rich waters were derived mainly from plagioclase in granite, not from hydrothermal calcites.

• Journal of the Korean Vacuum Society
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• v.6 no.2
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• pp.122-128
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• 1997

In this study, the PVDF organic thin films were fabricated by thermal evaporation deposition which is one of the dry-processing methods. The distance from heat source to substrate was 5 cm. The substrate temperature was maintained at $30 ^{\circ}C$ during deposition. The working pressure was about $2.0\times10^{-5}$Torr and the temperature of heat source was increased at the rate of 6 to $8^{\circ}C$/min. At $270^{\circ}C$, the shutter was opened and the deposition of PVDF has stared. As the electrical field intensity increased, $\alpha$ peaks such $530\textrm{cm}^{-1},795\textrm{cm}^{-1},1182\textrm{cm}^{-1}$ decreased, and $\beta$ peaks such as $510\textrm{cm}^{-1},1273\textrm{cm}^{-1}$ increased. The intensity of $530\textrm{cm}^{-1}$ peak was stronger than that of $510\textrm{cm}^{-1}$ peak velow the 71.4 kV/cm, intensity of electrical field. This result showed the characteristic of film mainly due to $\alpha$-mode. According to these results, the molecular structure of PVDF thin film is transformed from $\alpha$-mode with TGT or TG'T to $\beta$-mode with planar zigzag structure TT, as increasing of intensity of electrical field.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.1
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• pp.28-37
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• 2010

In this paper, the IC (Integrated Circuit) for multi-channel asynchronous communication was designed by using FPGA and VHDL language. The existing chips for asynchronous communication that has been used commercially are composed of one to two channels. Therefore, when communication system with two channels or more is made, the cost becomes high and it becomes complicated for communication system to be realized and also has very little buffer, load that is placed into Microprocessor increases heavily in case of high speed communication or transmission of high-capacity data. The designed IC was improved the function and performance of communication system and reduced costs by designing 8 asynchronous communication channels with only one IC, and it has the size of transmitter/receiver buffer with 256 bytes respectively and consequently high speed communication became possible. To detect errors between communications, it was designed with digital filter and check-sum logic and channel MUX logic so that the malfunction can be prevented and errors can be detected more easily and input/output port regarding each communication channel can be used flexibly and consequently the reliability of system was improved. It was composed and simulated logic of VHDL described by using Cyclone II Series EP2C35F672C8 and QuartusII V8.1 of ALTERA company. In order to show the performance of designed IC, the test was conducted successfully in QuartusII simulation and experiment and the excellency was compared with TL16C550A of TI (Texas Instrument) company and ATmegal28 general-purpose micro controller of ATMEL company that are used widely as chips for asynchronous communication.

• Journal of the Mineralogical Society of Korea
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• v.14 no.2
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• pp.128-136
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• 2001

The K-Ba complete solid solution of 7 synthetic hollandite-type minerals ($K_{2x}$ $Ba_{1-x}$ $Cr_2$/$Ti_{6}$ $O_{16}$ , x=0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0, respectively) are studied by the X-ray powder diffraction and Rietveld refinement to find structural transformation during substitution of $Ba^{2+}$ by $K^{+}$ in A site of the tunnel structure of hollandite. Rietveld indices indicate that $R_{wp}$ with respect to $R^{exp}$ ($R_{wp}$ $R_{exp}$ ) are in the range of 15.66%/20.90% and 14.74%/l9.37%, $R_{B}$ and S(Goodness of Fitness) are 6.45~8.97%, 1.45~1.63, respectively. Unit cell parameters of synthetic hollandites, space group 14/m, are a=10.1194(2)~10.0599(2)$\AA$, c=2.9572(6)~2.9512(7)$\AA$, and V=302.75~298.66$\AA^{3}$. Rutile formed as an impurity in those with more than 50% K contents in hollandite series. Substitution of Ba by K ion in a tunnel structure results in constant decrease of cell parameters, but is not sufficient enough to change the hollandite structure. Our data indicate that transformation of tetragonal 14/m to lower symmetry of monoclinic 12/m in hollandite structure may at least be affected by other cation substitution in same A site and/or by cation substitution in B site.

• Journal of Microbiology and Biotechnology
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• v.22 no.3
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• pp.292-300
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• 2012

We report the expression, purification, and characterization of L-asparaginase (AnsA) from Rhizobium etli. The enzyme was purified to homogeneity in a single-step procedure involving affinity chromatography, and the kinetic parameters $K_m$, $V_{max}$, and $k_{cat}$ for L-asparagine were determined. The enzymatic activity in the presence of a number of substrates and metal ions was investigated. The molecular mass of the enzyme was 47 kDa by SDS-PAGE. The enzyme showed a maximal activity at $50^{\circ}C$, but the optimal temperature of activity was $37^{\circ}C$. It also showed maximal and optimal activities at pH 9.0. The values of $K_m$, $V_{max}$, $k_{cat}$, and $k_{cat}/K_m$ were $8.9{\pm}0.967{\times}10^{-3}$ M, $128{\pm}2.8$ U/mg protein, $106{\pm}2s^{-1}$, and $1.2{\pm}0.105{\times}10^4M^{-1}s^{-1}$, respectively. The L-asparaginase activity was reduced in the presence of $Mn^{2+}$, $Zn^{2+}$, $Ca^{2+}$, and $Mg^{2+}$ metal ions for about 52% to 31%. In addition, we found that $NH_4{^+}$, L-Asp, D-Asn, and ${\beta}$-aspartyl-hydroxamate in the reaction buffer reduced the activity of the enzyme, whereas L-Gln did not modify its enzymatic activity. This is the first report on the expression and characterization of the L-asparaginase (AnsA) from R. etli. Phylogenetic analysis of asparaginases reveals an increasing group of known sequences of the Rhizobial-type asparaginase II family.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.21-21
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• 2018

본 연구는 북방계 식물에 속하는 두메우드풀[Woodsia ilvensis (L.) R.Br.]의 전엽체 증식 및 포자체 형성을 위한 적정방법을 구명하고자 수행되었다. 식물재료는 경상북도 의성군 일대에서 채취한 후 청주의 일반하우스에 이식하여 재배하였다. 포자 성숙기인 8월에 채종하여 발아시켰으며, 포자로부터 획득한 전엽체를 8주간 계대하면서 실험재료로 사용하였다. 전엽체 300mg을 메스로 다진 후 배지농도 및 종류(Knop, 1/4, 1/2, 1 및 2MS)를 달리하여 8주간 배양하였다. 배양실의 온도는 $25{\pm}1.0^{\circ}C$, 광도는 $30{\pm}1.0{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$(16/8h)로 조절되었다. 연구의 결과, 배지구성물질의 농도가 높았던 2MS배지에서 전엽체의 생체중이 12.4g으로 41배 증가하여 가장 높은 증식율을 나타냈다. 또한 배지구성물질의 농도가 적을수록 생체중의 증가폭도 함께 감소하는 경향을 보였다. 포자체 형성에 적합한 토양조건을 확인하고자, 원예상토, 피트모스, 펄라이트 및 마사토의 비율을 달리한 5종류의 혼합토양을 조성하여 사각분($7.5{\times}7.5{\times}7.5cm$)에 충진하였다. 다음으로 전엽체 1g을 핸드블랜더로 10초간 분쇄 후 충진된 사각분 위에 고르게 분주하여 14주간 재배하였다. 재배환경은 온도 $25{\pm}1.0^{\circ}C$, 광도 $43{\pm}2.0{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$(16/8h) 및 습도 $72{\pm}2.0%$로 조절되었다. 지베렐린 수용액이 포자체 형성에 미치는 영향을 조사하고자, 선행연구에서 선발된 토양조건을 기준으로 침지농도(0, 50, 100, $200mg{\cdot}L^{-1}$)를 조절하여 1시간 침지 후 상기와 동일한 방법으로 재배하였다. 연구의 결과, 원예상토와 펄라이트 또는 마사토를 2:1(v:v)로 혼용한 토양에서 사각분 당 109.5, 128.8개의 포자체가 형성되었다. 한편, 피트모스가 첨가된 처리는 포자체의 형성이 억제되는 경향을 나타냈다. 지베렐린 50과 $100mg{\cdot}L^{-1}$ 수용액에 침지한 처리에서 무처리에 비해 많은 사각분 당 각 177.0, 181.7개의 포자체가 형성되었으며, 생육도 양호하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.3
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• pp.297-303
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• 2024

In this study, KTN heterolayer thin films were fabricated by alternately stacking films of K(Ta_0.70Nb_0.30)O₃ and K(Ta_0.55Nb_0.45)O₃ synthesized using the sol-gel method. The sintering temperature and time were 750℃ and 1 hour, respectively. All specimens exhibited a polycrystalline pseudo-cubic crystal structure, with a lattice constant of approximately 0.398 nm. The average grain size was around 130~150 nm, indicating relatively uniform sizes regardless of the number of coatings. The average thickness of a single-coated film was approximately 70 nm. The phase transition temperature of the KTN heterolayer films was found to be approximately 8~12℃. Moreover, the 6-coated KTN heterolayer film displayed an excellent dielectric constant of about 11,000. As the number of coatings increased, and consequently the film thickness, the remanent polarization increased, while the coercive field decreased. The 6-coated KTN heterolayer film exhibited a remanent polarization and coercive field of 11.4 μC/cm² and 69.3 kV/cm at room temperature, respectively. ΔT showed the highest value at a temperature slightly above the Curie temperature, and for the 6-coated KTN heterolayer film, the ΔT and ΔT/ΔE were approximately 1.93 K and 0.128×10^-6 K·m/V around 40℃, respectively.

• Korean Journal of Food Science and Technology
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• v.36 no.6
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• pp.937-942
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• 2004

Physicochemical properties and mineral composition of seaweed salts prepared by incineration and osmotic dehydration methods were determined. As the incineration temperature increased, yield of seaweed salts, insoluble solids, pH, alkalinity, and oxidation-reduction potential (ORP) decreased. Alkalinity of salt prepared with sea tangle was higher than that of sea mustard. ORP decreased by incineration above $700^{\circ}C$, and was lower in salt with sea tangle. As incineration temperature increased, amounts of K and Ca in seaweed salt increased, whereas that of Mg decreased. Potassium and Ca contents of seaweed salt increased remarkably compared with those of common salt. Potassium content of sea tangle salt was higher than that of sea mustard. As incineration time increased, yield of seaweed salts, insoluble solid content, and pH decreased, whereas ORP of the salt increased. Potassium content of seaweed salt with incineration time, while Ca and Na contents decreased after incineration of 8 and 4 hr, respectively. Yield of seaweed salt by osmotic dehydration increased as immersion time in sea water increased. pH of salt from sea mustard was higher than that of sea tangle. ORP of seaweed salt dried three times was -128.8 mV, significantly lower than that of salt prepared by incineration method. As sea water immersion time increased, Mg content of seaweed salt increased significantly, while Ca content decreased. Potassium content of seaweed salt was higher in sea tangle salt. In case of salt prepared by incineration of residuals, pH increased with immersion time but ORP decreased.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.498-506
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• 2019

This study is based on a coating method that provides utilization value as a micronised powder for cosmetic raw materials using natural minerals buried in Bonghwa, Gyeongsangbuk-do in Korea. The mineral powder name is called Buseok, and chemical name is pumice powder. The results of a study on the efficacy of cosmetics are reported by the development of particulate powder to assess the performance of this powder. First of all, in order to coat the surface of this powder with oil, aluminum hydroxide was coated on the particulate surface and then coated with alkylsilan. In addition, it was coated with vegetable oil to prevent condensation of the powder and increase the dispersion in the oil phase. First; the particle size of pumice powder was from 10 to 50mm having porous holes on the surface of the particles. Second; The components of this powder contained $SiO_2$, $Al_2O_3$, $Fe_2O_3$, MgO, CaO, $K_2O_2$, $Na_2O$, $TiO_2$, $TiO_2$, MnO, $Cr_2O_3$, $V_2O_5$. Third: The particles of this powder have a planetary structure and are reddish-brown with porosity through SEM and TEM analysis. Fourth; the far-infrared radiation rate of this parabolic powder was $0.924{\mu}m$, and the radiative energy was $3.72{\times}102W/m^2$ and ${\mu}m$. In addition, the anion emission is 128 ION/cc, which shows that the coating remains unchanged. Based on these results, it is expected to be widely applied to basic cosmetics such as BB cream, cushion foundation, powderfect, and other color-coordinated cosmetics, sunblock cream, wash-off massage pack as an application of cosmetics. (Small and Medium Business Administration: S2601385)